The Enemy Inside
by pacejunkie
Summary: The TARDIS is taken over by a hostile entity that seeks to kill the Doctor and Donna and seize the ship. It’s a struggle for control with both the Doctor and his enemy using holographic images of the Doctor’s friends contained in the TARDIS memory...


**Title:** The Enemy Inside

**Rating:** PG/K+

**Characters:** Ten, Donna and assorted cameos by virtual past companions

**Summary:** The TARDIS is taken over by a hostile entity that seeks to kill the Doctor and Donna and seize the ship. It's a struggle for control with both the Doctor and his enemy using holographic images of the Doctor's friends contained in the TARDIS memory banks to help them. Contains a fair share of whump but also some cuteness and light.

**Word Count:** 7,635

**Disclaimer:** If _Doctor Who_ were mine, the Doctor and Donna would travel together forever.

* * *

Donna's mum had been right. _Men and their cars,_ she'd said.

They were no different no matter what planet they were from. The Doctor had been tinkering away under the TARDIS hood for the past two hours, with no more communication than the occasional mumble to himself. She suspected there were times when he would take random bits of the ship apart just to put them together again, like a nervous tic, something to do with his restless hands. Donna watched, with something less than mild interest, as she sipped her tea and read her book.

Life with the Doctor was never boring, but at times like these it could seem like something close to a normal life, almost domestic, although she'd never dare tell him that. Like her alien friend, Donna lived for the travel and excitement. The day it became ordinary was the day she packed it in, and she didn't intend to do that for a long time. This was just a lull, a time when they both recharged their batteries for the next adventure, which was never far off.

Still, she wasn't expecting it quite as soon as this.

Donna glanced up from her book to find a strange woman standing in front of her.

She looked human enough, petite and mature, with brown hair and a kind smile. Wearing a smart pantsuit, she stood just at the railing that circled the console. Hands folded patiently in front of her, it was as though she was in the supermarket queue and this was part of her normal everyday routine.

What was most strange about her was that she seemed to have appeared out of the proverbial nowhere, much as Donna herself had the first time. The Doctor had not been happy back when she had done it. He had said it was impossible. Donna wondered what he was going to say to this.

Then the woman spoke, paying no attention to Donna whatsoever.

"Doctor," she said, "you promised you wouldn't be a stranger. It's been so long. Have a cup of tea with me."

"Who's she?" asked Donna, alarmed and slightly affronted by the woman's familiarity, "How'd she get in here?"

She expected the Doctor to be equally alarmed, and to jump up and exclaim, "What?!" Instead, he merely glanced up casually at the sound of the woman's voice, and back to his temporal stabilisers or whatever they were called.

"Oh sorry," he told Donna, ignoring the sudden visitor, "That might have been me. That's Sarah Jane Smith. She used to travel with me. Only it's _not_ her, not really."

"What on earth are you on about," asked Donna, keeping one nervous eye on this stranger, who stood casually while they discussed her as though she weren't there.

"Doctor," the woman began again, "let's travel somewhere, just you and me, like we used to."

"Oh, don't mind _me_," Donna said, eyes rolling.

"Here, hang on a tic," the Doctor sighed, pushing himself up off the floor.

He flipped some switches on the console and she flickered like a projection and disappeared without a word of complaint.

"She's just a holographic projection," he explained, "Well, a bit more than that -- intelligence, awareness, and she's actually got some physical substance as well, powered by TARDIS energy."

"You travelled with a hologram?" asked Donna.

The Doctor looked offended. "No, of course not, I travelled with the real Sarah Jane, honestly," he protested, "The thing is, anyone who's ever travelled in the TARDIS leaves an imprint behind, like an echo of themselves. The TARDIS stores the images every time she backs up her systems. I can delete them if I want or I can save them, and...well..."

"Go on," Donna prods, with a wicked grin, "This is getting interesting. What do you save them for?"

The Doctor looked down at his trainers, "Sometimes I... well, it's a bit daft really, but...I call them up when I'm travelling alone...like...virtual company."

"That's...pathetic," said Donna, smiling, "you're pathetic you know that?"

"Don't tell anyone," said the Doctor, "I have an image to uphold. Anyway, I've got _you_ now, haven't I? I haven't accessed an imprint for months."

"Well why'd she appear just now then?" asked Donna.

"I'm not sure," he said, scratching his head while he checked the dials and readouts, "she's never done that before -- the TARDIS I mean, not Sarah. I was defragmenting the memory core. Perhaps I triggered something by mistake. I must have done."

"Maybe she's lonely," Donna joked.

The Doctor responded by looking up at the time rotor with a quizzical expression and giving his ship an affectionate pat.

_Men and their cars,_ thought Donna.

~*~

Donna was fast asleep in her room later that night, warm and comfortable under the covers, when she woke to the sound of someone yelling at her.

"What are you doing here?" the voice said through the dark.

Groggy, she thought she was still dreaming at first. She slowly opened her eyes, annoyed to have been woken out of a deep sleep. Squinting in the low lighting, she could make out only a shadowy shape standing at the foot of her bed. Her own voice caught in her throat when she opened her mouth and before she could make a sound it spoke again.

"Get out!" it screamed. "Leave him alone!"

Donna's heart started pounding. The voice was female and it sounded familiar. Fully awake now, she reached over to the bedside table and turned on the lamp.

But there was nothing there, she was alone.

_It could have been a dream,_ she thought, _but it felt so real._ Her hands still trembling and gripping the blanket, Donna lay with her eyes open, thinking about the projected image of Sarah Jane and how real _she_ had seemed. That hadn't been Sarah Jane in her room just now though, Donna knew this voice.

It was Martha Jones.

A furious Martha Jones at that and she had been screaming right at her. Disturbed, there was little more sleep to be had so Donna got up, dressed and went to find the Doctor. He was still tinkering away in the console room, the half full and forgotten cup of tea that she had left for him sat on the floor by his side. She didn't think he ever slept, not really, apart from the quick nap when he thought no one was looking. An hour or two a week seemed to be enough for him. Nine hundred years and very little sleep meant he must have gotten an awful lot done, she often thought. Humans slept a third of their lives away.

She told him about Martha appearing in her room.

"Quite like a good old fashioned haunting, eh?" he teased, amused.

"Doctor I'm serious," said Donna.

"Well you were thinking about Sarah Jane," he replied, sitting up and crossing his legs, "Are you sure this wasn't a dream?"

"Of course I'm sure," she insisted, "I didn't get a good look at her because it was dark but I was definitely awake, and I recognised her voice. It was Martha, shouting at me to go away."

"Go away where?" he asked.

"How should I know?" said Donna, "We got on quite well, Martha and me, why's she angry anyway?"

"I told you, it's not Martha, it's the TARDIS. She's just using Martha's imprint to..." the Doctor broke off, thinking. "Maybe you were right when you said she was lonely."

"Who, Martha?" she asked.

"No, the TARDIS!" he replied as though she were thick, springing up from the floor and turning to face the console.

"But it's a ship," laughed Donna, "I was joking. How can a ship be lonely?"

"The TARDIS is alive," he explained, looking up at the churning time rotor. When he spoke his voice sounded far away, dreamy, like he was talking to someone else. "She can sense danger, paradoxes, the emotions of her passengers... maybe she's trying to communicate something."

Then he broke from his trance and spun round to face her again, his words back to their usual mile a minute, "Or, maybe she's just acting jealous and misbehaving. I'll give her a bit more attention and she should calm down."

"Any more attention and it'll be _me_ who's jealous," Donna muttered, looking down at the spare parts ringing the console, and wondering what she did to annoy the TARDIS.

~*~

An hour later, Donna was having a distinct feeling of déjà vu. She was back in the console chair with her book and tea, only this time she was nodding off slightly from lack of sleep. The Doctor was as bright eyed as ever, putting the finishing touches on his latest round of maintenance work.

"There," he declared, straightening up and brushing down his lapels, "I've run a full system diagnostic, tuned the engine, rebuilt the stabilisers, increased the efficiency of the time rotor, tweaked the temporal harmoniser and topped off her fluids. She's got no more cause to complain."

He was just turning round to face Donna, quite pleased with himself, when at once his smile all but fell from his face like an avalanche.

"Donna, look out!" he shouted at her.

At the same time he leapt forward, reaching her in a single stride, grabbed her hand from her book and yanked her hard right down to the metal grating of the TARDIS deck. Donna's tea flew from her other hand, spraying them both with the hot liquid as the mug hit the floor with them and cracked in two. Throwing an arm around her the Doctor kept her pinned beneath him.

Donna had no idea what had happened at first but after throwing the Doctor a slightly irritated look for his apparent overreaction, she looked back at her chair.

Martha had returned, and this time she was armed with a large spanner from the TARDIS tool box. She had taken a swing at Donna from behind her and it was only the Doctor's quick reflexes that spared her brains from being splattered all over the newly refurbished console. Martha's blow had missed, and now she stood looking furious and ready to strike again.

The Doctor didn't plan to stay cowering for long. Still holding Donna's arm, keeping her down, he fished in his jacket pocket for the sonic screwdriver. Making a quick one handed adjustment, he aimed and pressed the button. The familiar whirr rang out and Martha turned to static before flickering out altogether like a candle in the wind. Its holder gone, the very real spanner fell to the floor with a loud clatter.

When he was satisfied the Doctor sprang up and checked the console scanner.

"Now do you believe me?" asked Donna, getting up from the floor and rubbing at her bruised elbows.

"Come on," moaned the Doctor, ignoring Donna, smacking at the console screen, "I promised to show you more attention didn't I? You're behaving like a spoilt child."

"Doctor, why would the TARDIS just try to _kill_ me?" Donna asked.

"She'd never," he protested as he typed, "It has to be a computer virus, something that's corrupting the imprints." He continued working and after a moment he sighed, frustrated, "I can't find anything. The best way to eliminate it is to set down somewhere, shut her down and purge and reboot all the systems."

"Sounds like a plan," said Donna, "I don't think I'll get another night's sleep until something is done, it's getting downright spooky in here."

"I'm just looking for a suitable place to land," he said, fingers flying, "We might be there a while. It may as well be someplace nice."

Making a selection, he set the coordinates and reached for the handbrake but never got the chance to grasp it before they were plunged into total darkness.

"Doctor, what have you done now?" called Donna, hoping evil Martha wasn't back, lurking around in the dark.

She couldn't see a thing, but that didn't stop her trying to look over her shoulder. She felt a bit too vulnerable for her liking. Through the dark came the Doctor's reply and his voice alone helped to calm her.

"It wasn't me," he said. "I think it's the..."

His sentence was cut short as the TARDIS abruptly dropped out from beneath their feet and then spun. For an instant she felt weightless, and then she was roughly pulled back down, the ship tumbling and tossing the Doctor and Donna around like a pair of socks in a dryer.

Donna's feet flew out from under her and she flailed, trying to find something to grab onto to halt her momentum. She got a hold of what felt like the Doctor's tie for a second only to lose it again. She finally gave up and just threw her arms over her head and curled up tight, hoping it would soon stop and that she wouldn't be impaled on something sharp before it did.

The room shook and turned over so many times she couldn't tell the floor from the ceiling anymore, and her body was getting battered. Throughout it all, Donna heard only her own screams, dull thuds and cries of pain from the Doctor each time he must have collided with something, and then nothing.

Just before she was about to be sick, everything stopped but the darkness.

~*~

The Doctor opened his eyes and released his grip. He had landed underneath the console and grabbed onto the centre column at some point, hoping to ride it out like he had the great San Francisco earthquake of 1906. When the motion stopped the Doctor slowly brought up one hand, then another, and hauled himself to his feet with a groan. It was still pitch black.

"Not my best landing I'll admit," the Doctor said, rubbing at a colossal bump on his head and wincing.

Something had temporarily interfered with the artificial gravity and inertia fields, he surmised, sending them into a tailspin. Most likely it was the same virus that was playing havoc with the stored personality imprints, so the same solution he had already proposed should correct both problems.

The first order of business was to get the lights back on, he decided. He tried the console panel, but the controls were dead. Groping his way to a secondary panel in the wall, he found the switch for the emergency lights and activated it. They shone bright red, not too bright, but enough that he could see that he was alone.

"Donna?" he called.

He checked under the console and the chair, then around the perimeter of the room, anywhere she might have fallen or gotten stuck. He called for her again, more loudly. She wasn't there.

He knew he could ordinarily locate her human signal with the computer but the controls were locked to him. The time rotor was gently humming again, showing him that the TARDIS still had life, but she was blocking him out, preventing him from gaining access to her systems. The virus was spreading.

There was no rebooting the TARDIS now, he knew, and even if he could do it would mean shutting down all life support and he couldn't do that with Donna still lost inside somewhere. The Doctor was certain she was still on the ship; the turbulence must have thrown her into another room, which meant she could be anywhere, and with a corrupted imprint on the loose she was likely in danger.

_Right, find Donna first, then fix the ship,_ he decided.

He left the console room and started down the first hallway, then instinctively turned left. The TARDIS was made up of a labyrinth of corridors that led to different rooms at different times. Under normal circumstances, the TARDIS guided you along, sensing your intended destination and helping you to reach it. The Doctor didn't normally need any such guidance – he had sensory perception of his own which allowed him to find his way – but for companions it was dead useful. Without it, Donna would have gotten lost trying to find her bedroom each night as it tended to move. If those systems were offline, Donna could quite literally be going in circles right now trying to find him.

Making a few more turns he began checking the various rooms as they appeared left and right, calling out to Donna as he went. He passed her bedroom, the kitchen, the botanical gardens, but all were empty. Without the TARDIS' help it was a painfully slow process, and once again the Doctor's thoughts and concerns went to his beautiful ship. It was when you lose someone that you realise how dependent you were on their constant presence as a source of strength and the TARDIS was no different. It wasn't just that his ship was broken; it was something more, like a part of him was broken too. Without the TARDIS he was something less, unable to reach his full potential. He was a time traveller, but it was only because of the TARDIS, and without that, the Doctor didn't know what he would be.

Pushing his darker thoughts aside, he continued his search, coming to the last set of rooms in the wing. He had reached his own bedroom. The Doctor stuck his head in for a quick look, but instead of finding Donna, he was confronted once again with the image of Martha.

Having lost her spanner she had replaced it with the Doctor's cricket bat from his room. She took a vicious swing at his head as soon as it had appeared in the doorway. The Doctor ducked and jumped back, barely avoiding it. The bat cracked against the doorframe. Martha lifted it again and pursued him.

"There you are!" she raged, as the Doctor backed away, "How many times did I save your life but I was never good enough was I? Why did you never love me?!"

_This is awkward,_ thought the Doctor.

He turned and ran ducking into the first room he saw with a furious Martha on his tail. Pushing open the double doors, he quickly drew up short when he realised he was in the pool room, standing at the edge of the deep end. He should have smelled the chlorine sooner but in his haste he had paid no attention.

Martha entered just behind him, cricket bat raised.

"Now, that's got sentimental value," he told her, hands out in front, "I think you should just put it down."

"Means more to you than I did I'm sure," Martha fumed, "like everything else."

"Just listen to me," he tried, "you don't know what you're doing. Your file's been corrupted. You have to trust me I can help."

"I know what I'm doing," she replied with a look of disgust, "I'm putting an end to all of my problems."

_Don't listen to her,_ the Doctor told himself, _this isn't really Martha._

But her words still stung him. The TARDIS constructed these profiles from imprints of the real passenger's emotions. There had to be some trace amount of anger and pain of rejection however small inside Martha that the virus picked up on and corrupted into something much bigger. He knew Martha would never act this way, but the truth was the TARDIS couldn't make something from nothing. It had exploited those feelings it found and was now using them against him. The thought disturbed him, and not for the first time he felt a tremendous surge of guilt as he stood there now, trapped poolside.

But there was something more, something bigger than his mistakes with Martha that troubled him now. If Martha's imprint could be abused this way that meant that there were potentially others, people who have travelled in the TARDIS with a petty grudge against him, a sliver of resentment, a hint of jealousy, anything that could be turned deadly.

The Doctor's mind raced. He knew that he had gone through and deleted certain imprints in the past that he didn't want to have around, like Margaret the Slitheen and that pesky Graske. Everyone else he'd had good relationships with, he thought, so there shouldn't be any more negative emotions the virus could exploit.

_Except for one,_ he realised, as he felt both hearts sink in his chest.

There was one, the one he could never bring himself to delete, because it was too much like killing him all over again, and they were the only ones left. He instantly regretted that moment of weakness now.

"Oh no," he said out loud, closing his eyes.

"Goodbye Doctor," spat Martha as she brought the cricket bat round.

At the same time the Doctor heard someone rise up out of the pool behind him with a noisy splash. He turned around in time to glimpse the Master, grabbing at his legs from his place in the water with a devilish grin.

"Fancy a swim?" the imprint asked.

Then the bat made contact with the back of the Doctor's head.

As he fell forward, stars in his eyes, the Doctor wasn't surprised at all when the Master pulled him deep down into the water.

~*~

At first she thought she was dreaming again. She was stretched out, but instead of her warm comfortable bed it felt hard and rough, with neither pillow nor blanket. Donna opened her eyes and saw only legs of chairs and a low settee. She was on a thinly carpeted floor in some kind of lounge. She sat up slowly, her head spinning. Then she remembered.

The TARDIS had been falling and she was thrown – but where? She didn't recognise the room she was in, she had never seen it before. The only clues she had that she was even still in the TARDIS were the coral struts and round lights that resembled the console room, her bedroom, the library and everywhere else she had been. When she was feeling stronger she rose, testing her legs. Donna didn't know what had happened but she knew she had to find the Doctor. She left the lounge and went out into the corridor.

Despite the TARDIS' considerable size Donna normally found her way around quite easily but this time she was feeling particularly disoriented. Perhaps she had hit her head harder than she thought because it felt as though she were going in circles. She turned right and as she passed the lounge for the third time, she sighed heavily.

_This time I'll turn left,_ she told herself.

She started off again, taking the opposite turn and nearly bumped into him speeding round the corner.

"Doctor!" she shouted, "Where've you been?"

"Looking for you," he said, taking her hand. "Come on, this way!"

Donna went along without question, following him through wordless twists and turns, simply trusting. _The Doctor always knew what to do in a crisis,_ she knew, _he'd sort this out._ A few minutes later he led her into the library of all places.

"What are we doing here?" she asked, looking around at the stacks for some clue. "Have you worked out how to fix the TARDIS or do we have to look it up in one of those DIY books?"

Behind her, she heard a latch closing. The Doctor had shut the library doors and locked them. She turned to face him, but when he turned round he seemed strange, different somehow. His face was dark and menacing. Donna had seen that look directed at enemies but never at her.

"You're staying right here with me," he said, eyes blazing.

Donna backed away as the realisation dawned on her in horror.

"You're not the Doctor," she said. "You're another one of those imprint things like Martha." _I should have known,_ she realised silently, _of course the TARDIS would have an imprint of the Doctor as well._

"Where is he?" she demanded.

"We've taken care of that," the imprint said, moving slowly toward her, "and you're next."

She looked around frantically for a means of escape but the imposter had locked the only doors. With nothing else to do she started pulling large hardcover books off the shelves and throwing them at the image of the Doctor. He dodged some and batted away more and continued moving forward. In a panic, she threw more books at his feet, trying to trip him up, slow him down, anything, using both hands, grabbing armfuls and emptying entire shelves into a pile. He was getting closer, and Donna was running out of both time and room. She was about to be trapped up against the last bookcase on the far wall.

As she struggled to defend herself she thought, _This isn't real. Remember the Doctor said it's just a projection. So if it's a projection there has to be a power source, some way of turning it off._

She pulled more books from the shelves and then turned over the entire empty bookcase itself to block the image's path. He stood on the opposite side of the fallen fixture, and began to climb over. Donna turned to face the wall searching for a fire extinguisher or anything she could use as a weapon. Instead, she spied a control panel of blinking lights that had been hidden behind the case.

_A power source,_ she realised.

Donna ripped the panel's cover from the wall to reveal a collection of wires connected to the lights. She looked back at the projection of the Doctor who now looked worried, and Donna knew her guess had been correct.

"What are you doing," he said angrily. "Don't touch that! I order you to stop!"

"Now I know you're not the Doctor," Donna said, "because he learned a long time ago that he can't tell me what to do."

She grabbed a fistful of wires and pulled. Sparks flew, singeing her fingers. The projection screamed, flickered and vanished.

~*~

More than two metres down the Doctor struggled underwater with the Master. He was being pulled deeper and deeper down by his ankles. His lungs burned as he bucked and fought; he was able to hold his breath for longer than the average human but even he was running out of air, and the exertion he was expending in an involuntary panic response was causing his oxygen supply to run out quicker.

The Master just smiled with maniacal glee and held on tight. As a computer imprint that did not require air, he would most definitely win this battle, and there seemed to be nothing the Doctor could do about it but fight to the end. He was determined not to make it easy for him at the very least, but he was getting drowsy. Sleep was beginning to sound very good...

With the last of his strength he kicked out weakly with both legs, and to his great surprise he felt a release of pressure. He looked down and saw the Master's image flicker in the water and then vanish. Wasting no time, the Doctor swam to the surface. He broke through with a painful gasp, reached out for the pool's edge and pulled himself out. Coughing up water, dripping on the concrete and tile, he laid there in the puddle, body exhausted but his mind still sharp. He couldn't stop himself thinking as he recovered.

_This is not just a simple computer virus,_ he realised, _the TARDIS would never try to kill me no matter how corrupt its systems. That means someone has seized control. _

In what seemed like defiance to his epiphany, it was still several minutes before he had the energy to move, his head pounding from the assault with the cricket bat that he had nearly forgotten about. Finally he pushed himself up, left the pool area and set off back toward the console room, leaving a trail of water in his wake like bread crumbs. If there was a hostile entity aboard the TARDIS finding it was now his first priority. He had to know what it was after. He would just have to trust that Donna was clever enough to stay out of trouble for a while.

The Doctor was just passing the wardrobe room when the Master reappeared, flickering back into existence like the second coming and blocking his path.

"Where are you running off to Doctor?" he asked. "We were having such a good time."

"Who are you," the Doctor demanded, "identify yourself!"

The Master responded but when he did his voice was changed, as though another were speaking through him. "I am Umbazi," it said, "and I claim this ship for salvage under the Derelict and Abandoned Vessels Act of the Skifory Convention of the Galactic Realm of the Angelus Cluster. This vessel has crossed into Skifory space and thus I declare it derelict and open to claim."

"What have you done to Donna?" the Doctor asked.

"The only way a vessel can be legally claimed for salvage is if there are no living, sentient inhabitants on board," Umbazi explained. "She is to be eliminated along with you."

"Isn't murder illegal on your planet too?" The Doctor asked him.

"Yes quite right, I'm afraid that bit will have to be our little secret," Umbazi replied.

The entity in the Master's form stepped towards him and the Doctor sensed his time for information gathering was coming to a close. Reaching into his pocket, he removed his sonic screwdriver and aimed it to disrupt the projection, but when he pressed the button, nothing happened. Holding it to his ear and shaking it as he backed off, he heard a sloshing sound and realised it was waterlogged and wouldn't work.

"It seems I have many more tools at my disposal than you at the moment," said Umbazi. "This is truly a miraculous vessel. Allow me to demonstrate."

At that the Doctor's head was filled with a burst of energy from the TARDIS core. He grabbed his head and dropped to his knees as an explosion went off between his ears. The pain was unbelievable, an intense overload of sound, light and piercing sensation that refused to stop. He screamed as Umbazi calmly stood over him.

"You're doomed to fail," the Doctor said, covering his ears and looking up at his tormentor, "The TARDIS can't kill me... no matter what."

"Perhaps not," the entity conceded, "but I can certainly kill your friend, so perhaps you ought to consider cooperating and surrender your ship to me willingly."

"No," moaned the Doctor, but it was all he managed to say before passing out and sagging to the floor.

~*~

Climbing over her homemade mountain range of books, Donna freed herself from the library, setting off again to find the real Doctor this time. She had to be extra cautious now; she knew she could no longer trust her own eyes and these imprints were everywhere. Staying close to the walls Donna peered around each corner carefully before proceeding, narrowly missing a Martha imprint twice and a man who she swore looked like Harold Saxon, the former prime minister. She had to assume that they were all dangerous and so she did her best to avoid being spotted.

Worried, she couldn't help thinking about what the imposter Doctor had said, that the Doctor had been "taken care of". Donna had to find him and make sure he was all right. Whatever had gone wrong with the ship, she was confident that he could work it out, but right now it was likely he needed her help.

She wanted to call out for him but was afraid of attracting the attention of the imprints. Tiptoeing her way along, Donna was reminded of the time she was left skulking on her own aboard the Sontaran ship. Terrified, she had managed to subdue one soldier, and then reconnect the transporter so the Doctor could rescue her and the TARDIS. The Doctor had needed her help then and she had not let him down, despite the fact that she had very little confidence in herself and was convinced she was about to die. Swallowing her fear, she had rose to the occasion and it was because of that experience and the Doctor's faith in her that she knew that she could surprise herself again, as she had already proven in the library, and do whatever was required of her.

Turning at random, Donna kept moving until eventually the corridors began to look different and she knew she was no longer doubling back. Then ahead of her she spotted something – small footprint sized puddles on the corridor floor surrounded by water droplets. She looked up at the ceiling; there didn't seem to be any leak or obvious source, so they must have been tracks left by someone. The trail led to the left and right, but after a long time spent wandering she sensed that to go left was back where she came from, so she chose right and followed it, hoping she wouldn't run into an imprint that had just decided to take a bath or something.

Three more turns and one winding corridor later, she found him at the end of his trail, alone and unconscious in the hallway. She ran forward and fell to her knees beside the Doctor.

"Doctor," she said, trying to rouse him, "Doctor, wake up."

He stirred and then flinched at the sight of her.

"Are you all right?" she asked him.

"Donna," he said, bleary and blinking, "is that really you?"

"I could ask you the same question," she replied. "You tried to kill me in the library just now."

"I did?" he said, confused. "I mean, that wasn't me."

"Yeah, I worked that one out thanks," she told him.

He tried sitting up with difficulty and Donna helped him. When she did she got a good look at his drenched clothes and hair. Donna thought it made him appear even skinnier if that was possible.

"Look at you, you're soaking," she said. "What happened?"

The Doctor looked down at his wrinkled suit that clung to his body and began wringing water from his tie. His eyes darted everywhere, unfocused, still blinking as though sensitive to the light.

"I had a bit of an accident," he said finally.

"Next you'll tell me this place has got a swimming pool," said Donna.

"Well...," he began but Donna shushed him.

"Did you hear something?" she said, "Those things, they're still out there. What are they?"

The Doctor told her about Umbazi and what he was after. As bad as the news was, Donna was still relieved to learn that the TARDIS didn't hate her after all.

"When the one that looked like you came after me," she explained, "I pulled the plug on him, cut the power and he just disappeared."

"That was _you_?" the Doctor said, the pieces falling into place. When Donna had cut the power on the imprint of himself in the library, it must have also caused the Master in the pool to vanish, allowing him to escape. "Donna you're brilliant! If the images can be turned off from any power source they can be turned _on_ as well. I might be able to access certain imprints that can help us get the TARDIS back, but the console is still locked, I need a secondary access panel, come on."

He sprang up with renewed energy, took off down the hall and Donna followed. His shoes squeaked as he ran but the Doctor didn't seem to notice. They ran until they reached a large square panel at the base of one wall. The Doctor was about to remove the cover when Donna stopped him.

"Wait!" she said, "You can't do that you're drenched! Do you want to electrocute yourself?"

"Oh," he said, looking down at his suit again, "Sorry, I'm still a bit dazed, I forgot. We passed the wardrobe, I'll get changed. Wait here but try to stay out of sight."

Before she could argue that she didn't fancy being on her own again, he was gone. Donna crouched down in a corner and waited, counting the seconds and watching for any unwanted visitors. When he returned not five minutes later he was in an identical but dry brown suit and trainers. Donna wondered how many of them he had. He had towelled off his hair and though it was still damp and wild it was no longer dripping.

Crouching down, the Doctor removed the cover of the access panel and immediately lay down on his back and crawled inside up to his knees to reach the wiring. Donna sat beside him. After a moment of fiddling in silence, the Doctor spoke and when he did his voice reverberated like he was talking into a coffee tin.

"The thing is," he began, "we're only seeing the imprints of certain people and there's a reason for that. Umbazi is exploiting all the imprints he can but there are some he can't exploit, because he needs a way in and he hasn't got one. But I have."

The Doctor flipped a switch while at the same time Donna nearly jumped out of her skin as the image of a woman appeared before her. Donna brought her arms up; ready to fight or flee but the woman had no weapon and made no threatening gestures. Donna didn't know her but like Harold Saxon she was sure she had seen her somewhere before. She was young and very pretty, and blonde.

"Wait," said Donna, pointing at the image and taking a wild guess, "is that...?"

"Rose Tyler!" announced the Doctor with unchecked glee, crawling back out of the access panel and getting up from the floor.

"Hello you," Rose greeted him with an enormous smile.

The Doctor straightened his jacket and smoothed back his hair. He grinned madly.

"Hello yourself," he said.

Donna's eyes rolled northward, "Oh now this really is _weird_." Like she had with Sarah Jane, Donna began to feel invisible or at the very least as superfluous as a third wheel. She decided someone needed to snap them out of it. "I hate to break up the reunion but if you wouldn't mind we have a _crisis_ here!"

"Oh yeah, sorry," said the Doctor, nodding in understanding. He explained to the Rose imprint about Umbazi trying to take over the ship.

"Right," she replied, "typical Thursday then."

The Doctor let out a small chuckle, and Donna realised not for the first time that he must have missed her terribly. "I'm locked out but you can access the TARDIS controls and give them back to me," he told Rose.

"Too right I can," she said, "let's go."

Rose led the way and the Doctor and Donna followed. As they went Donna whispered to the Doctor. "Are you sure you can trust her?" she asked him.

"Of course I can," said the Doctor, affronted, and for a moment Donna wasn't sure if he was talking about the computer imprint or Rose herself. Then he elaborated. "Don't worry, I'm not that gullible. I checked her file and she's uncorrupted. Right now she's the closest thing to TARDIS communication that we have."

"Not a bad interface either, eh?" Donna teased.

The Doctor made a coughing sound as though trying to swallow his embarrassment, "Well, there's that. Plus she's got the added feature that she won't try to kill us, which is always a good thing."

A moment later they reached the console room. They entered but got no further than the outer railing before Donna saw that their way to the controls was blocked by a young black man brandishing a long chain with one end wrapped around his fist like a weapon.

"Rose is mine, Doctor," said the man, "and you can't have her."

"Oh no, not _you_," groaned the Doctor. "I forgot all about you."

"Well yeah you would now wouldn't you," he replied, swinging the chain in a threatening manner, "seeing as you stole Rose from me."

"Who's he now?" asked Donna.

"Doesn't matter," said the Doctor, "I'm done playing charades. Give up Umbazi, you can't win this!"

"I think you're wrong there, boss," said the image of Mickey.

The imprint raised his chain and came forward. The Doctor stepped in front of Donna but out in front of them both stepped Rose. She stared down the young man with her hands on her hips.

"Mickey, stop it now!" she demanded.

"You should have stayed with me Rose!" bellowed a now furious Mickey. "We were happy until he came along!"

"You're kidding me, is this for real?" said Donna watching over the Doctor's shoulder, "Are they fighting for control of the TARDIS or auditioning for _Corrie_?"

"Get out of my way," Mickey continued.

"No," Rose said, "I won't let you hurt him."

"I warned you," said Mickey and he swung the chain.

It wrapped around Rose's wrist and she held on with surprising strength. The two grabbed hold of each other and locked in a struggle as the Doctor and Donna watched.

"Can't you pull the plug on him," asked Donna, "like I did with you?"

"Not without also losing Rose," said the Doctor, "and I need her. She's our only link to the TARDIS right now. Well, in a way, I suppose you could say she is the TARDIS. If I break the connection I might not get it back."

Donna could tell when the Doctor was feeling helpless – he grew silent and still, drained of his usual spirit. The two imprints continued to fight over the console and as they did, Donna noticed that both of their images start to flicker and fade.

"Doctor, look!" she cried.

"No!" shouted the Doctor in alarm, "Rose!"

In an instant they both vanished. The Doctor rushed forward and slammed his fist down on the console.

"Can you get her back?" asked Donna.

The Doctor checked the scanner. "No," he groaned, "the file is corrupt. But there might be someone else."

The Doctor ran to the wall panel where he had turned on the lights earlier and pulled out the wires, rerouting them. After a few tries another imprint appeared. This one was more Donna's type -- tall, dark, strong and handsome. The man wore a long wool RAF coat and to Donna's surprise when he saw the Doctor he saluted him.

"Captain Jack Harkness reporting for duty, sir," Then the man relaxed and smiled a cheeky, boyish grin, "Doctor, as I live and breathe."

"Not exactly," said the Doctor, "but you'll do."

"Ooh that's more like it," cooed Donna at the sight of Jack, "but I'm going to have to start keeping a list. I hope you've made more friends than enemies."

Jack turned to Donna, noticing her for the first time. He took her hand and kissed it, "A pleasure to meet you darling."

Donna couldn't help herself and she giggled like a schoolgirl. "Oh, I wouldn't mind accessing your imprint every now and again," she winked.

"Not _now_, we've got work to do!" complained the Doctor, shouting at them both. He turned to Jack again, "Get me my TARDIS back and you can flirt all you want."

"Yes sir, right away sir," said Jack as he ran to the console screen. His fingers danced over the controls as though they were an extension of himself, which Donna supposed, they were. "Umbazi has imprinted himself into the main computer," Jack explained as he worked. "That's how he's controlling everything. If I could just access the code for his imprint I might be able to delete it and purge him from the system. Then all you'll be left with is a helpless alien running loose on board."

"I can handle that," said the Doctor, "do it."

He tried a few commands and then frowned. "This interface is locked, even to me. I have to work from inside. Give me a few minutes."

The image of Jack stepped back and closed his eyes. Donna saw as he began to sparkle and swirl into what appeared to be a blue gaseous state. The cloud then floated towards the time rotor and vanished inside. The column glowed brighter in intensity.

The Doctor took his place and checked the screen. "It's working," he declared, "He's in there, purging the imprints."

"What, all of them?" asked Donna.

"Yeah, it's best that way," said the Doctor, "clean sweep. Sorry, I lied about that flirt, but I'll introduce you to the real Jack someday if you want."

"Nevermind that, did he fix it?" she asked.

The Doctor tried the controls. "Oh yes, good man! Now I can use the internal scanners to locate the real Umbazi."

It took another minute and then the Doctor said, "I found him. He's hiding in the antigravity room...and I've just locked him in." He put on his glasses and squinted at the screen, "Blimey, he's small, looks like a mosquito, no wonder he slipped in so easily. With a brain that tiny the TARDIS probably didn't even recognise him as a threat. I'll let him float for a while and then we'll pop him in a jar, set down on the nearest planet and drop him off...about a thousand years before his time, but after the invention of pesticides, how does that sound?"

"Sounds about right to me," said Donna. She put a hand on his shoulder, "I'm sorry about your imprints."

"Nah, it's all right," he said, "who needs holograms? Nothing beats the real thing."

Donna smiled. "Once we're rid of him how about a holiday?" she suggested.

The Doctor smiled back and took her hand. "Anywhere you like," he said. "I reckon the TARDIS deserves one too. But let's take along our insect repellent just in case."


End file.
